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KIN 104 > Module 3 - Neuromechanics > Flashcards

Module 3 - Neuromechanics Flashcards

1
Q

Central nervous system (CNS)

A

Brain + spinal cord protected by boney structures

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2
Q

Peripheral nervous system (PNS)

A
  • Nerves outside the CNS
  • Somatic component includes sensory (senses) + motor (movement, muscle cells) nerves
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3
Q

Autonomic nervous system (ANS)

A
  • Control system of body functions such as breathing, cardiovascular function, etc.
  • Sympathetic + parasympathetic
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4
Q

Components of brain

A
  • Cerebrum (bulk of grey matter, neuron cell bodies)
  • Diencephalon
  • Cerebellum
  • Brain stem
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5
Q

Cerebrum (components + function)

A
  • Cerebral cortex
  • Hippocampus + amygdala (long-term memory)
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6
Q

Diencephalon (components + function)

A
  • Thalamus (sensory)
  • Hypothalamus (homeostasis)
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7
Q

Brain stem (components + function)

A
  • Midbrain
  • Pons
  • Medulla (cardiovascular function)
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8
Q

Spinal cord

A

Runs through vertebra, connects to peripheral on the sides of each vertebra

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9
Q

Grey matter

A
  • Cell bodies, dendrites, axon terminals
  • Areas of synaptic connections
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10
Q

White matter

A
  • Axons
  • Pathways between grey matter areas
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11
Q

Spinal cord to PNS

A

Grey + white matter of spinal cord –> ventral + dorsal roots (projections coming out of vertebra) –> go on to form PNS

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12
Q

Peripheral nerves

A
  • Nerve –> collection of many neurons (cells)
  • Motor nerves: efferent neurons –> control effectors such as skeletal muscles
  • Sensory nerves: afferent neurons –> detect stimuli + relay that info to CNS
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13
Q

Neurons

A
  • Basic information processing unit: receives input, process info, + provides output
  • Neurons are excitable cells; send/stop action potential
  • In a balancing act (tug-of-war) between “turn on” (depolarize + receive info from other neurons) + “turn off” (stay at -70mV)
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14
Q

Neuron anatomy

A
  • Processing section: nucleus, soma (cell body), dendrites (receive info from other neurons)
  • Communication section: axon (where AP transmitted, can be very long), axon terminal (where synapses form w/ other neurons)
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15
Q

Axon hillock

A
  • Where processing section connects to communication section (via axon)
  • Decides if AP is transferred to axon (is there enough AP?)
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16
Q

Membrane potential

A
  • Negative at rest (-70mV)
  • Depolarization = membrane potential becomes +ve (+20mV) (once AP surpasses thershold)
  • Repolarization/hyperpolarization = membrane potential becomes negative (-70mV)
  • Has a refractory period (opening/closing of ion channels) –> then resting state
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17
Q

Glial cells

A

Provide support to neuron function (helps with structure, metabolism, + repair) (helper/support cells)

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18
Q

Synapse

A
  • Structure permitting communication b/w 2 neurons
  • Where neuron interacts w/ another neuron/cell type
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19
Q

Action potential

A

Change in electrical potential that can travel along a cell membrane (-ve to +ve –> depolarization)

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20
Q

Neurotransmitter

A

A chemical messenger that transmits a message b/w cells

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21
Q

Cell to cell communication

A
  • Action potential travelling down an axon is an electrical signal
  • This electrical signal converted to chemical signal at axon terminals
  • Chemical signal converted to electrical signal at post-synaptic neuron
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22
Q

Measuring the nervous system

A
  • Structure: structural imaging –> MRI
  • Function: neuronal activity –> functional imaging, electroencephalography (EEG) –> measures electrical activity of brain, electrophysiology
  • Behaviour: times (e.g. reaction time), non-timed (errors, response)
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23
Q

Biopotential

A
  • Electrical potential measured between 2 points in living cells, tissues, and organisms (electrical diff. b/w 2 points) –> e.g. neurons, skeletal muscles
  • Electrodes, amplifiers, + electrical activity
  • EMG, ECG, EEG
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24
Q

Electroencephalography (EEG)

A
  • Measuring electrical activity (biopotentials) arising from the CNS
  • What is being measured? –> neuronal activity –> APs (de/repolarization)
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25
Q

Muscle

A
  • Tissue made up of many muscle cells + associated connective tissue
  • 3 main types: skeletal, cardiac, smooth
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26
Q

Skeletal muscle cell

A
  • Muscle fibre/myocyte –> individual cell that when activated produced force that can lead to motion
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27
Q

Sarcomere

A

Fundamental unit of skeletal + cardiac muscle. MANY sarcomeres arranged in sequence within single myofibril + many myofibrils make up a muscle cell

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28
Q

Myofilaments

A

Sarcomeres are composed of highly organized arrangement of myofilaments (composed mainly of actin + myosin) that interact w/ each other to generate force (slide across each other)

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29
Q

Skeletal muscle structure (levels of organization)

A
  • Full, highly organized, full of machinery used to generate force (proteins, structures, etc.)
  • Fascicle: unit of a muscle cell
  • Muscle fibre: unit of a fascicle
  • Myofibril: unit of a muscle fibre (long strands of sarcomere)
  • Sarcomere: unit of myofibril (ends are Z-lines)
  • Sarcolemma: cell membrane
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30
Q

Cross bridge

A
  • Binding of actin to myosin myofilaments + change in confirmation of myosin
  • Cross bridge cycle: process involving attachment, conformation change + detachment (with ATP) that generates force
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31
Q

Sliding filament theory

A

Theory explaining mechanism of muscle contraction associated with cross bridge cycling + sliding of myofilaments past each other to generate force

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32
Q

Cross bridge cycle overview

A
  • Sarcomere shortens when myosin heads in thick myofilaments form cross bridges w/ actin in thin filament
  • Formation of cross bridge –> initiated when Ca2+ released from sarcoplasmic reticulum bind to troponin –> changes shape
  • Tropomyosin moves away from myosin binding site on actin –> myosin head binds to actin + forms cross bridge (myosin head must also be activated before cycle can begin –> ATP hydrolysis provides energy to activate into cocked position)
  • Ends when Ca2+ is actively transported back to SR, troponin returns to original shape –> tropomyosin covers myosin binding site on actin
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33
Q

Cross bridge cycle steps

A

1) Cross bridge formation: myosin head binds to actin, inorganic P released, bond is stronger
2) Power stroke: ADP released + activated myosin head pivots, sliding thing myofilament toward centre of sarcomere
3) Cross bridge detachment: another ATP binds to myosin head –> link b/w myosin head + actin weakens –> myosin head detaches
4) Reactivation of myosin head: ATP hydrolyzed –> energy reactivates myosin head –> cocked position

As long as actin binding sites exposed –> cross bridge cycle repeats –> thin myofilaments pulled towards each other –> sarcomere shortens

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34
Q

Motor neuron

A

Neuron that synapses w/ skeletal muscle cells

35
Q

Motor unit

A

Motor neuron + ALL muscle cells it innervates (neuron interacts w/ diff. cell type) –> 100s-1,000s-100,000s

36
Q

Neuromuscular junction

A

Synapse b/w motor neuron + a skeletal muscle cell

37
Q

Muscle action potential

A

Action potential (depolarization –> repolarization on membrane of skeletal muscle cell)

38
Q

Neuromuscular activation

A
  • Electrical: depolarization of motor neuron (neuronal AP)
  • Chemical: neurotransmitter (acetylcholine (ACH)) release at neuromuscular junction
  • Electrical: depolarization of muscle fibre
  • Mechanical: cross-bridge formation + sarcomere shortening
39
Q

How can you control the amount of force a whole muscle generates?

A
  • Muscle fibres activate in an ALL or NONE manner (1 motor neuron –> all muscle cells it innervates/AP arrives at one muscle –> ACH released –> muscle contracts)

1) Motor unit recruitment
2) AP frequency

In general: increase in AP frequency –> increase in force

40
Q

What determine the maximum isometric force a whole muscle cell could generate (assume maximal potential frequency and recruitment + optimal length)?

A
  • Bigger muscle –> more sarcomere –> more force
  • Cross-sectional area of a muscle –> more muscle cells –> more sarcomeres –> more cross bridges –> more force
41
Q

Electromyography (EMG)

A

Technique to measure electrical activity produced by muscles (muscle APs) that occurs when muscle is stimulated

42
Q

Surface EMG

A
  • Skin prep + electrode placement –> very important
  • Need to know direction of muscle fibres
  • Pro: relatively easy technique, less risk of damage/infection
  • Con: limited to superficial muscle, unsure of which muscle is producing electrical activity (risk of interference)
43
Q

Intramuscular EMG

A
  • Small needle is inserted into a muscle + electrical activity is recorded directly
  • Pro: specific choice of muscle
  • Con: invasive (skilled technician needed)
44
Q

Axes of EMG graph

A
  • y-axis: mV, V
  • x-axis: time
45
Q

Relationship b/w EMG amplitude + muscle force

A
  • Positive relationship b/w RAW (unfiltered, no mathematical manipulation) EMG + muscle force
  • As EMG increases, force increases
  • CANNOT compare RAW EMG b/w diff. muscles (e.g. diff. size) OR b/w people
  • Slight delay/lag time w/ force production compared to EMG
46
Q

Stimulus response

A
  • Series of events that req. afferent info + involve some sort of efferent response/effect
  • Stimulus presented –> SENSORY: info going to CNS through afferent neurons –> CORTICAL: neural info is processed (combined with prior behavioural instructions) –> MOTOR: an effect is determined + is transported through efferent neurons –> muscles activated to perform task
  • ALL steps take time (short time)
47
Q

Reaction time

A
  • Time it takes CNS to sense, process, + initiate response to stimulus (from stimulus to onset of response)
  • Afferent –> processing –> efferent
48
Q

Movement time

A
  • Time it takes person to execute specific movement (does not include reaction time)
  • Time from onset muscle activation (EMG) to end of response
  • From muscle activated (start) to end of response
49
Q

Response time

A
  • Reaction time + movement time
  • Total time from stimulus detection –> end of stimulus response
50
Q

What factors is reaction time dependent on?

A

Stimulus intensity + modality (type)
- Cognitive/neural impairment
- Age
- Presence/absence of neurological disease + inheritence
- Medications/drugs
- Environment (distractions)
- Sex

SRT: simple reaction time
CRT: choice reaction time

51
Q

Simple reaction time (SRT)

A
  • Only 1 stimulus + 1 response
  • e.g. “Hear something –> push a button”
52
Q

Choice reaction time (CRT)

A
  • Number of diff. stimuli presented each required diff. response
  • Reaction time gets longer w/ more stimuli
  • e.g. various pitch sounds –> press diff. button for each
53
Q

Dual-task interference

A
  • Simultaneous performance of 2 tasks often leads to performance deficits in component tasks
  • Thought to be proof of capacity limitation in cognition
  • Can’t to Z things at the same time as fast is if they were separate

Multi-tasking:
- Possible, some people better than others
- Aspect of learning + practice

54
Q

Agonist

A

Muscle primarily responsible for a movement (e.g. biceps brachii in bicep curl)

55
Q

Antagonist

A

Muscle that opposes the movement of agonist (e.g. triceps brachii in bicep curl)

56
Q

Agonist + antagonist dependency

A
  • Dependent on posture + movement
  • e.g. Knee flexion + extension while sitting vs lying down
  • Gravity always affects body –> posture + movement change agonist vs antagonist
57
Q

Reciprocal contraction (/activation) + benfits

A
  • Simultaneous activation of agonist + inactivation (relaxation) of antagonist
  • Maximizes amount of force it can produce (does not need to overcome agonist)
58
Q

Co-contraction + benefits

A
  • Simultaneous activation of agonist + antagonist
  • Stabilizes joint
  • e.g. Carrying heavy load –> stability of joint needed to support weight + prevent injury
59
Q

Graphing joint kinematics + EMG

A

CANNOT graph without kinematics (EMG only) –> don’t know what’s going on

60
Q

Biomechanics

A

Study of effects + control of forces that act on + are produced by living beings

61
Q

Kinematics

A

Study of MOTION of objects (w/out reference to the FORCES that caused the motion)

62
Q

Kinetics

A

Study of FORCES that cause motion

63
Q

Linear kinematics terms

A
  • Displacement (m)
  • Velocity (m/s)
  • Acceleration (m/s^2)
64
Q

Angular kinematics terms

A

ROTATIONAL

  • Angular displacement (rad)
  • Angular velocity (rad/s)
  • Angular acceleration (rad/s^2)
65
Q

Force

A

LINEAR
- Action/influence that moves body or influences movement of the body
- UNIT: newtons (N)
- Internal forces: created primarily by skeletal muscles
- External forces: created by ground (ground reaction force), external loads, other individuals, + from passive sources (e.g. wind resistance)

66
Q

Moment

A

ANGULAR
- “Moment of force”
- Force that tends to change the rotational motion of an object
- UNIT: Nxm
- M +ve: counter-clockwise
- M -ve: clockwise

67
Q

Vectors

A
  • Have magnitude (length) + direction
  • Tail and head
  • A non vertical/horizontal vector is a sum of its vertical + horizontal components
68
Q

Moment arm

A
  • Perpendicular distance from application of force
  • Distance b/w point of rotation + application of force
  • Larger moment arm –> larger moment of force (rotational)
69
Q

Centre of mass (COM)

A

Point in centre of object where all of the mass of object is equally distributed in all directions

70
Q

Centre of mass (COM) and gravity

A

Force of gravity acts in downward direction (-y) through the centre of mass (COM) of an object

71
Q

Force of gravity

A
  • Mass x acceleration due to gravity (9.8m/s^2)

F = m x a
F = 5kg x -9.8m/s^2
F = -49N

72
Q

Moment calculation

A

M = F x d

Approach 1:
- F = force applied
- d (moment arm) = perpendicular distance b/w axis of rotation + line of force
- No 90 degree angle –> trig

Approach 2:
- F = force vector component that is perpendicular to segment
- d (moment arm) = distance from axis of rotation to point of application of force
- USING THIS ONE

73
Q

Muscle force and moments

A
  • Must consider all moments acting on a segment –> must consider the sum of the moments
  • If a segment is stationary –> sum of M = 0
74
Q

Kinematics measurement

A
  • Visual observation
  • Goniometer (instrument to measure angles): hand held/electronic
  • Inertial sensors: measure acceleration
  • Optical/magnet motion capture: gold standard for measuring kinematics
75
Q

Goniometer types + pros/cons

A

Hand held:
- Pro: can do everywhere on anyone
- Con: guess, estimate, not very accurate, stuck with static

Electronic:
- Pro: mobile
- Con: may not be as accurate

Potentiometer:
- Pro: accurate joint angle
- Con: tethered to one spot, immobile

76
Q

Inertial sensors pros/cons

A

High-end:
- Pro: accurate
- Con: expensive

Personal (e.g. Apple Watch):
- Pro: affordable in comparison, easy to use
- Con: not as accurate

77
Q

Optical motion capture

A
  • Gold standard (one of best techniques, go-to, reliable) of measuring kinematics
  • Cameras tracking dots: know exactly where each joint is in 3D (inertia + joint angle), can calc. displacement, velocity, acceleration, etc.
  • Pro: really accurate/gold standard
  • Con: expensive, software + trained people required
78
Q

Kinetics measurement

A
  • Manual assessment
  • Dynamometer: device to measure force, moment, or power (hand held/electronic)
  • Force plates: instrument to measure ground reaction forces
79
Q

Manual muscle testing pros/cons

A
  • Want to understand where deficits in body are through comparison w/ healthy parts
  • Pro: can do it anywhere
  • Con: lots of training required, not very accurate (subjective, don’t know how many N)
80
Q

Dynamometer types + pros/cons

A

Hand held, hand grip:
- Pro: objective (N, kg), measures amount of force
- Con: have to be able to brace yourself to oppose the force

Isokinetic dynamometer:
- Pro: can test most joints, can control many variables (joint angle, speed (fixed/variable), resistance), completely adjustable, 360 degree rotation
- Con: Expensive

81
Q

Force plates

A
  • Gold standard in measuring kinetics (forces)
  • Can get a sense of interaction w/ environment while doing things
  • Need kinematics to go with kinetics for full picture
  • Pro: can measure force in all 6 directions + moments, really accurate
  • Con: alone –> no idea of kinematics, really sensitive, some are anchored into ground/others mobile
82
Q

What is included in the foundation of biomechanical research?

A
  • EMG (muscle activation)
  • Kinematics (movement)
  • Kinetics (forces)

Combined = full picture

83
Q

Gold standards of biomechanics

A
  • Optical motion capture: kinematics
  • Force plates: kinetics

KIN 104 (4 decks)

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